Phospholipid-Anchored Ligand Conjugation on Extracellular Vesicles for Enhanced Cancer Targeting.

Extracellular vesicles (EVs) are recognized as potential candidates for next-generation drug delivery systems. However, the inherent cancer-targeting efficiency is unsatisfactory, necessitating surface modification to attach cell-binding ligands. By utilizing phospholipase D from Streptomyces in combination with maleimide-containing primary alcohol, the authors successfully anchored ligands onto milk-derived EVs (mEVs), overcoming the issues of ligand leakage or functional alteration seen in traditional methods. Quantitative nano-flow cytometry demonstrated that over 90% of mEVs are effectively modified with hundreds to thousands of ligands. The resulting mEV formulations exhibited remarkable long-term stability in conjugation proportion, ligand number, size distribution, and particle concentration, even after months of storage. It is further shown that conjugating transferrin onto mEVs significantly enhanced cellular uptake and induced pronounced cytotoxic effects when loaded with paclitaxel. Overall, this study presents a highly efficient, stable, cost-effective, and scalable ligand conjugation approach, offering a promising strategy for targeted drug delivery of EVs.

Pure-Shift-Based Proton Magnetic Resonance Spectroscopy for High-Resolution Studies of Biological Samples.

Proton magnetic resonance spectroscopy (1H MRS) presents a powerful tool for revealing molecular-level metabolite information, complementary to the anatomical insight delivered by magnetic resonance imaging (MRI), thus playing a significant role in in vivo/in vitro biological studies. However, its further applications are generally confined by spectral congestion caused by numerous biological metabolites contained within the limited proton frequency range. Herein, we propose a pure-shift-based 1H localized MRS method as a proof of concept for high-resolution studies of biological samples. Benefitting from the spectral simplification from multiplets to singlet peaks, this method addresses the challenge of spectral congestion encountered in conventional MRS experiments and facilitates metabolite analysis from crowded NMR resonances. The performance of the proposed pure-shift 1H MRS method is demonstrated on different kinds of samples, including brain metabolite phantom and in vitro biological samples of intact pig brain tissue and grape tissue, using a 7.0 T animal MRI scanner. This proposed MRS method is readily implemented in common commercial NMR/MRI instruments because of its generally adopted pulse-sequence modules. Therefore, this study takes a meaningful step for MRS studies toward potential applications in metabolite analysis and disease diagnosis.

CTCOSY-JRES: A high-resolution three-dimensional NMR method for unveiling J-couplings.

Two-dimensional (2D) J-resolved spectroscopy provides valuable information on J-coupling constants for molecular structure analysis by resolving one-dimensional (1D) spectra. However, it is challenging to decipher the J-coupling connectivity in 2D J-resolved spectra because the J-coupling connectivity cannot be directly provided. In addition, 2D homonuclear correlation spectroscopy (COSY) can directly elucidate molecular structures by tracking the J-coupling connectivity between protons. However, this method is limited by the problem of spectral peak crowding and is only suitable for simple sample systems. To fully understand the intuitive coupling relationship and coupling constant information, we propose a three-dimensional (3D) COSY method called CTCOSY-JRES (Constant-Time COrrelation SpectroscopY and J-REsolved Spectroscopy) in this paper. By combining the J-resolved spectrum with the constant-time COSY technique, a doubly decoupled COSY spectrum can be provided while preserving the J-coupling constant along an additional dimension, ensuring high-resolution analysis of J-coupling connectivity and J-coupling information. Moreover, compression sensing and fold-over correction techniques are introduced to accelerate experimental acquisition. The CTCOSY-JRES method has been successfully validated in a variety of sample systems, including industrial, agricultural, and biopharmaceutical samples, revealing complex coupling interactions and providing deeper insights into the resolution of molecular structures.

Reduced contrast sensitivity function is correlated with changes to cone photoreceptors in simple high myopia.

Purpose: To investigate the contrast sensitivity function (CSF) changes in simple high myopia (SHM) and evaluate the correlations between these changes with the early changes in the retinal microstructure. Methods: This prospective study comprised 81 subjects, 20 with emmetropia (EM), 26 with low myopia and moderate myopia (LM/MM), and 35 with SHM. The area under the log CSF curve (AULCSF) and the cut-off spatial frequency (Cut-off SF) were employed as measures of CSF. Adaptive optics (AO) was employed to quantify the cone density, spacing, and regularity. The thickness and blood flow of the retinal sublayers were determined from vertical and horizontal optical coherence tomography angiography (OCTA) A-scans. Swept-source optical coherence tomography (SS-OCT) was employed to analyze the choroidal thickness (CT) and choroidal vascularity using a custom algorithm. Differences in the retinal and choroidal parameters, cone distribution, AULCSF, and Cut-off SF were compared among the three groups. Multivariate linear mixed models were used to elucidate the associations between photoreceptor morphological alterations, retinal and choroidal parameters, and AULCSF. Results: The AULCSF and Cut-off SF were significantly lower in the SHM group compared to the EM and LM groups (p < 0.05). The SHM group had less cone density, larger cone spacing, and lower cone regularity than the EM and LM/MM groups (p < 0.05). Moreover, the thickness of the inner segment of photoreceptors (IS), retinal pigment epithelium (RPE) layer and choroid were reduced, and the outer segment of photoreceptors (OS) was thicker in the SHM group compared to the EM and LM/MM groups (all p < 0.05). A longer axial length (AL) was correlated with decreased AULCSF, cone density, and cone spacing (r = -0.800 to 0.752, all p < 0.050). Additionally, decreased CSF was correlated with lower cone density (r = 0.338, p = 0.035). Conclusion: Decreased contrast sensitivity was observed in patients with SHM and cone density was significantly correlated with reduced AUCSF.

A Ternary Inverter Based on Hybrid Conduction Mechanism of Band-to-Band Tunneling and Drift-Diffusion Process.

In this paper, a novel transistor based on a hybrid conduction mechanism of band-to-band tunneling and drift-diffusion is proposed and investigated with the aid of TCAD tools. Besides the on and off states, the proposed device presents an additional intermediate state between the on and off states. Based on the tri-state behavior of the proposed TDFET (tunneling and drift-diffusion field-effect transistor), a ternary inverter is designed and its operation principle is studied in detail. It was found that this device achieves ternary logic with only two components, and its structure is simple. In addition, the influence of the supply voltage and the key device parameters are also investigated.

Genome-wide identification of resistance genes and response mechanism analysis of key gene knockout strain to catechol in Saccharomyces cerevisiae.

Engineering Saccharomyces cerevisiae for biodegradation and transformation of industrial toxic substances such as catechol (CA) has received widespread attention, but the low tolerance of S. cerevisiae to CA has limited its development. The exploration and modification of genes or pathways related to CA tolerance in S. cerevisiae is an effective way to further improve the utilization efficiency of CA. This study identified 36 genes associated with CA tolerance in S. cerevisiae through genome-wide identification and bioinformatics analysis and the ERG6 knockout strain (ERG6Δ) is the most sensitive to CA. Based on the omics analysis of ERG6Δ under CA stress, it was found that ERG6 knockout affects pathways such as intrinsic component of membrane and pentose phosphate pathway. In addition, the study revealed that 29 genes related to the cell wall-membrane system were up-regulated by more than twice, NADPH and NADP+ were increased by 2.48 and 4.41 times respectively, and spermidine and spermine were increased by 2.85 and 2.14 times, respectively, in ERG6Δ. Overall, the response of cell wall-membrane system, the accumulation of spermidine and NADPH, as well as the increased levels of metabolites in pentose phosphate pathway are important findings in improving the CA resistance. This study provides a theoretical basis for improving the tolerance of strains to CA and reducing the damage caused by CA to the ecological environment and human health.

Spatial mapping of corneal biomechanical properties using wave-based optical coherence elastography.

Quantifying the mechanical properties of the cornea can provide valuable insights into the occurrence and progression of keratoconus, as well as the effectiveness of corneal crosslinking surgery. This study presents a non-contact and non-invasive wave-based optical coherence elastography system that utilizes air-pulse stimulation to create a two-dimensional map of corneal elasticity. Homogeneous and dual concentration phantoms were measured with the sampling of 25 × 25 points over a 6.6 × 6.6 mm2 area, to verify the measurement capability for elastic mapping and the spatial resolution (0.91 mm). The velocity of elastic waves distribution of porcine corneas before and after corneal crosslinking surgery were further mapped, showing a significant change in biomechanics in crosslinked region. This system features non-invasiveness and high resolution, holding great potential for application in ophthalmic clinics.

Compact multipass-laser-beam antenna for NV sensor sensitivity enhancement.

Large-area, highly uniform microwave field radiation and efficient excitation of fluorescence are the key to achieving high sensitivity sensing of the NV (nitrogen-vacancy) magnetometer. In this paper, we report a compact multipass-laser-beam antenna for NV ensemble color centers sensing. The antenna not only provides a tridimensional uniform magnetic field, but also can be used for efficient excitation of the NV fluorescence. The optimal size of the antenna and the angle of laser incidence are determined by the multi-physics field simulation software COMSOL. For an equivalent excitation power, the designed structure increases the path length of the excitation beam by up to three orders of magnitude, up to the level of m, compared to the conventional direct beam mode. Finally, this method increased the sensitivity by a factor of 60 realized a magnetic field sensitivity of 2.8 nT/√Hz in the range of 10-100 Hz. This work provides an experimental method for the design of integrated NV magnetometers.

Progress of Nonmetallic Electrocatalysts for Oxygen Reduction Reactions.

As a key role in hindering the large-scale application of fuel cells, oxygen reduction reaction has always been a hot issue and nodus. Aiming to explore state-of-art electrocatalysts, this paper reviews the latest development of nonmetallic catalysts in oxygen reduction reactions, including single atoms doped with carbon materials such as N, B, P or S and multi-doped carbon materials. Afterward, the remaining challenges and research directions of carbon-based nonmetallic catalysts are prospected.

Selection, identification and crystal structure of shark-derived single-domain antibodies against a green fluorescent protein.

Shark variable domain of new antigen receptors (VNARs) are the smallest naturally occurring binding domains with properties of low complexity, small size, cytoplasmic expression, and ease of engineering. Green fluorescent protein (GFP) molecules have been analyzed in conventional microscopy, but their spectral characteristics preclude their use in techniques offering substantially higher resolution. Besides, the GFP molecules can be quenched in acidic environment, which makes it necessary to develop anti-GFP antibody to solve these problems. In view of the diverse applications of GFP and unique physicochemical features of VNAR, the present study aims to generate VNARs against GFP. Here, we identified 36 VNARs targeting eCGP123, an extremely stable GFP, by phage display from three immunized sharks. These VNARs bound to eCGP123 with affinity constant KD values ranging from 6.76 to 605 nM. Among them, two lead VNARs named aGFP-14 and aGFP-15 with nanomolar eCGP123-binding affinity were selected for in-depth characterization. aGFP-14 and aGFP-15 recognized similar epitopes on eCGP123. X-ray crystallography studies clarified the mechanism by which aGFP14 interacts with eCGP123. aGFP-14 also showed cross-reaction with EGFP, with KD values of 47.2 nM. Finally, immunostaining analyses demonstrated that aGFP-14 was able to bind effectively to the EGFP expressed in both cultured cells and mouse brain tissues, and can be used as a fluorescence amplifier for EGFP. Our research demonstrates a feasible idea for the screening and production of shark-derived VNARs. The two high-affinity VNARs developed in the study contribute to the diversity of GFP sdAbs and may enhance the applications of GFP.

Melatonin reduces radiation-induced ferroptosis in hippocampal neurons by activating the PKM2/NRF2/GPX4 signaling pathway.

Ferroptosis is a type of regulated cell death that is dependent on iron and reactive oxygen species (ROS). Melatonin (N-acetyl-5-methoxytryptamine) reduces hypoxic-ischemic brain damage via mechanisms that involve free radical scavenging. How melatonin regulates radiation-induced ferroptosis of hippocampal neurons is yet to be elucidated. In this study, the mouse hippocampal neuronal cell line HT-22 was treated with 20µM melatonin before being stimulated with a combination of irradiation and 100 µM FeCl3. Furthermore, in vivo experiments were performed in mice treated with melatonin via intraperitoneal injection, which was followed by radiation exposure. A series of functional assays, including CCK-8, DCFH-DA kit, flow cytometry, TUNEL staining, iron estimations, and transmission electron microscopy, were performed on cells as well as hippocampal tissues. The interactions between PKM2 and NRF2 proteins were detected using a coimmunoprecipitation (Co-IP) assay. Moreover, chromatin immunoprecipitation (ChIP), a luciferase reporter assay, and an electrophoretic mobility shift assay (EMSA) were performed to explore the mechanism by which PKM2 regulates the NRF2/GPX4 signaling pathway. The spatial memory of mice was evaluated using the Morris Water Maze test. Hematoxylin-eosin and Nissl staining were performed for histological examination. The results revealed that melatonin protected HT-22 neuronal cells from radiation-induced ferroptosis, as inferred from increased cell viability, decreased ROS production, reduced number of apoptotic cells, and less cristae, higher electron density in mitochondria. In addition, melatonin induced PKM2 nuclear transference, while PKM2 inhibition reversed the effects of melatonin. Further experiments demonstrated that PKM2 bound to and induced the nuclear translocation of NRF2, which regulated GPX4 transcription. Ferroptosis enhanced by PKM2 inhibition was also converted by NRF2 overexpression. In vivo experiments indicated that melatonin alleviated radiation-induced neurological dysfunction and injury in mice. In conclusion, melatonin suppressed ferroptosis to decrease radiation-induced hippocampal neuronal injury by activating the PKM2/NRF2/GPX4 signaling pathway.

Properties of Pacific white shrimp (Litopenaeus vannamei) collagen and its degradation by endogenous proteinases during cold storage.

Many factors are responsible for the diminished quality of shrimp during cold storage, while the role of collagen has rarely been studied. This study therefore investigated the relationship between collagen degradation and changes of textural properties of Pacific white shrimp, and its hydrolysis by endogenous proteinases. The textural properties of shrimp decreased gradually along with disruption of shrimp muscle tissues, and the chewiness property of shrimp muscle showed a linear relationship with collagen contents in muscle during 6-day-storage at 4 °C. Pepsin-solubilized collagen in shrimp muscle consisted of one α1 chain and two α2 chains, revealing a typical tripeptide sequence (i.e., Gly-X-Y) in their molecules. In addition, collagen could be hydrolyzed by crude endogenous proteinases extracted from shrimp hepatopancreas, and serine proteinase plays a critical role in the process. These findings strongly suggested that the quality reduction of shrimp during cold storage is closely associated with collagen degradation.

Prognostic Analysis of a Hypoxia-Associated lncRNA Signature in Glioblastoma and its Pan-Cancer Landscape.

BACKGROUND: Hypoxia is an important clinical feature of glioblastoma (GBM), which regulates a variety of tumor processes and is inseparable from radiotherapy. Accumulating evidence suggests that long noncoding RNAs (lncRNAs) are strongly associated with survival outcomes in GBM patients and modulate hypoxia-induced tumor processes. Therefore, the aim of this study was to establish a hypoxia-associated lncRNAs (HALs) prognostic model to predict survival outcomes in GBM patients. METHODS: LncRNAs in GBM samples were extracted from The Cancer Genome Atlas database. Hypoxia-related genes were downloaded from the Molecular Signature Database. Co-expression analysis of differentially expressed lncRNAs and hypoxia-related genes in GBM samples was performed to determine HALs. Six optimal lncRNAs were selected for building HALs models by univariate Cox regression analysis. RESULTS: The prediction model has a good predictive effect on the prognosis of GBM patients. Meanwhile, LINC00957 among the six lncRNAs was selected and subjected to pan-cancer landscape analysis. CONCLUSION: Taken together, our findings suggest that the HALs assessment model can be used to predict the prognosis of GBM patients. In addition, LINC00957 included in the model may be a useful target to study the mechanism of cancer development and design individualized treatment strategies.

Research Progresses and Applications of Fluorescent Protein Antibodies: A Review Focusing on Nanobodies.

Since the discovery of fluorescent proteins (FPs), their rich fluorescence spectra and photochemical properties have promoted widespread biological research applications. FPs can be classified into green fluorescent protein (GFP) and its derivates, red fluorescent protein (RFP) and its derivates, and near-infrared FPs. With the continuous development of FPs, antibodies targeting FPs have emerged. The antibody, a class of immunoglobulin, is the main component of humoral immunity that explicitly recognizes and binds antigens. Monoclonal antibody, originating from a single B cell, has been widely applied in immunoassay, in vitro diagnostics, and drug development. The nanobody is a new type of antibody entirely composed of the variable domain of a heavy-chain antibody. Compared with conventional antibodies, these small and stable nanobodies can be expressed and functional in living cells. In addition, they can easily access grooves, seams, or hidden antigenic epitopes on the surface of the target. This review provides an overview of various FPs, the research progress of their antibodies, particularly nanobodies, and advanced applications of nanobodies targeting FPs. This review will be helpful for further research on nanobodies targeting FPs, making FPs more valuable in biological research.

Predictors for short-term successful weaning from continuous renal replacement therapy: a systematic review and meta-analysis.

The systemic review and meta-analysis aimed to identify the predictors for short-term successful weaning from CRRT in severe AKI patients. PubMed, Embase, the Cochrane Library, and grey literature were searched for relevant studies investigating variables for short-term successful weaning from CRRT to August 2022. Our criteria included patients with AKI who required CRRT but excluded patients with kidney failure. The pooled odds ratios (OR) and 95% confidence intervals (CI) were calculated using fixed-effect (I2≤50% and P-value of the Q statistic > 0.1) or random-effect models (I2>50% or p-value of the Q statistic ≤ 0.1) as appropriate. Our search yielded 11 studies and described 11 variables. The pooled analysis showed that chronic kidney disease (OR = 0.638, 95% CI: 0.491-0.829), CRRT duration (OR = 0.913, 95% CI: 0.882-0.946), and urine output at the cessation of CRRT (per 100 mL/day increase) (OR = 1.084, 95% CI: 1.061-1.108) were predictive factors for short-term successful weaning from CRRT. Male (OR = 0.827, 95% CI: 0.627-1.092), diabetes mellitus (OR = 0.970, 95% CI: 0.761-1.237), and sepsis (OR = 0.911, 95% CI: 0.717-1.158) were unrelated to the short-term weaning from CRRT. The relationship between hypertension, use of vasopressors or inotropes at the starting of CRRT, use of vasopressors or inotropes at the cessation of CRRT, use of diuretics at the cessation of CRRT, serum creatinine at the cessation of CRRT, and short-term weaning from CRRT remains unclear. Additional prospective studies are needed to evaluate this relationship further.

A biometrics-based mutual authentication and key agreement protocol for TMIS using elliptic curve cryptography.

Telecare Medicine Information System (TMIS) refers to a medical model that uses communication and information technology to realize multiple medical functions such as remote disease diagnosis, treatment, and health care. Because TMIS is carried out on an insecure public Internet, a large number of mutual authentication and key agreement protocols for TMIS have been proposed to protect the privacy of patients. Recently, Ostad-Sharif et al. proposed a novel anonymous authentication and key agreement scheme for TMIS. In this work, we will demonstrate that Ostad-Sharif et al.'s scheme exists the problems of strong authentication and inefficient password change, and it cannot resist the off-line password guessing attack. To overcome the weaknesses found in Ostad-Sharif et al.'s scheme, we propose a biometrics-based mutual authentication and key agreement protocol for TMIS, making full use of the advantages of one-way hash function and elliptic curve cryptosystem (ECC). The security of the proposed scheme is formally proved under the widely used random oracle model (ROM), and various known malicious attack resistances also are presented by the heuristic discussion. Compared with the existing related schemes, the computation cost and communication overhead of our scheme are reduced by 74.5% and 27.3% respectively.

Involvement of MMP-9 in collagen degradation of sea bass (Lateolabrax japonicus): Cloning, expression, and characterization.

Disintegration of intramuscular connective tissue is responsible for postmortem tenderization of fish muscles during chilled storage. Matrix metalloproteinase-9 (MMP-9) was reported to be involved in this process, whereas the mechanism has not been revealed. In the present study, purified type I and V collagens from the connective tissues of sea bass (Lateolabrax japonicus) muscles were first prepared. These two kinds of collagens comprise three polypeptide chains (α), forming a typical triple-helical domain as determined by circular dichroism. The complete coding region of MMP-9 containing an open reading frame of 2070 bp encoding 689 amino acid residues was then cloned. The recombinant MMP-9 catalytic domain (rcMMP-9) was expressed in Escherichia coli and exhibited high hydrolyzing activity toward gelatin. Besides, rcMMP-9 was effective in degrading type V collagen rather than type I collagen at 4°C. The enzymatic activity of rcMMP-9 was highly pH-dependent, and its enzymatic activity under neutral and basic conditions was higher than that under acidic conditions. Metal ion Ca2+ was necessary for the maintenance of rcMMP-9 activity, whereas Zn2+ inhibited its activity. Our present study indicated that MMP-9 is responsible for the disintegration of intramuscular connective tissues by cleaving type V collagen during postmortem tenderization of fish muscle. PRACTICAL APPLICATION: Elucidation the involvement of MMP-9 in collagen degradation will deliver a reference for the prevention of muscular protein decomposition during chilled storage of fish fillets.

Enhancing Spin-Based Sensor Sensitivity by Avoiding Microwave Field Inhomogeneity of NV Defect Ensemble.

The behavior of the magnetic field sensitivity of nitrogen-vacancy (NV) centers as a function of microwave power and the inhomogeneous distribution of MW fields was systematically studied. An optimal structure for exciting spin structures by MW signals was designed using two parallel loop antennas. The volume of the homogeneous regions was approximately 42 mm3, and the associated diameter of the diamond reached up to 5.2 mm with 1016 NV sensors. Based on this structure, the detection contrast and voltage fluctuation of an optically detected magnetic resonance (ODMR) signal were optimized, and the sensitivity was improved to 5 nT/√Hz. In addition, a pulse sequence was presented to fully eliminate the MW broadening. The magnetic field sensitivity was improved by approximately one order of magnitude as the π-pulse duration was increased to its coherence time. This offers a useful way to improve the sensitivity of spin-based sensors.

Relationships of Matrix Metalloproteinase 1 and a Tissue Inhibitor of Metalloproteinase to Collagen Metabolism in Haliotis discus hannai.

In response to physical, chemical, and/or biological stimuli, considerable tissue self-degradation occurs in abalone, causing severe post-harvest quality loss. During this process, the extracellular matrix (ECM) is greatly degraded by endogenous proteases. The main component of the ECM is collagen, primarily type I collagen. Although the activity of matrix metalloproteinases (MMPs), which can specifically degrade collagen, is precisely regulated by tissue inhibitors of MPs (TIMPs), indicating that MMPs and TIMPs play crucial roles in the regulation of tissue self-degradation, few studies have reported the interaction between MMPs and TIMPs. In this study, we reveal collagenases to participate in postmortem tissue self-degradation of Haliotis discus hannai by degrading type I collagen. The recombinant MMP-1 catalytic domain (rMMP1c) of abalone with high purity and enzyme activity is expressed using a prokaryotic expression system. The optimum temperature and pH for rMMP1c are 37 °C and 7.0, respectively. The thermal denaturation temperature of rMMP1c is 67.0 ± 0.9 °C. Ethylenediamine tetraacetic acid (EDTA) and 1,10-phenanthroline can completely inhibit rMMP1c activity, while Ba2+, Ca2+, and Mg2+ can significantly elevate it. TIMP is also expressed using HEK 293F cells. Recombinant TIMP (rTIMP) shows good inhibitory activity toward rMMP1c. Inhibition kinetics analyses reveal rTIMP to be a competitive inhibitor of rMMP1c. Biolayer interferometry reveals that rTIMP can effectively bind with rMMP1c, with an equilibrium dissociation constant value of 263 nM. rMMP1c effectively degrades type I collagen γ-ß-α chains in turn, and rTIMP can significantly inhibit rMMP1c degradation activity. These results provide a theoretical basis for the study of MMP and TIMP interaction and elucidate the possible mechanism for abalone tissue self-degradation.

Screening and Characterization of Shark-Derived VNARs against SARS-CoV-2 Spike RBD Protein.

The receptor-binding domain (RBD) of the SARS-CoV-2 spike protein is the major target for antibody therapeutics. Shark-derived variable domains of new antigen receptors (VNARs) are the smallest antibody fragments with flexible paratopes that can recognize protein motifs inaccessible to classical antibodies. This study reported four VNARs binders (JM-2, JM-5, JM-17, and JM-18) isolated from Chiloscyllium plagiosum immunized with SARS-CoV-2 RBD. Biolayer interferometry showed that the VNARs bound to the RBD with an affinity KD ranging from 38.5 to 2720 nM, and their Fc fusions had over ten times improved affinity. Gel filtration chromatography revealed that JM-2-Fc, JM-5-Fc, and JM-18-Fc could form stable complexes with RBD in solution. In addition, five bi-paratopic VNARs, named JM-2-5, JM-2-17, JM-2-18, JM-5-18, and JM-17-18, were constructed by fusing two VNARs targeting distinct RBD epitopes based on epitope grouping results. All these bi-paratopic VNARs except for JM-5-18 showed higher RBD binding affinities than its component VNARs, and their Fc fusions exhibited further enhanced binding affinities, with JM-2-5-Fc, JM-2-17-Fc, JM-2-18-Fc, and JM-5-18-Fc having KD values lower than 1 pM. Among these Fc fusions of bi-paratopic VNARs, JM-2-5-Fc, JM-2-17-Fc, and JM-2-18-Fc could block the angiotensin-converting enzyme 2 (ACE2) binding to the RBD of SARS-CoV-2 wildtype, Delta, Omicron, and SARS-CoV, with inhibition rates of 48.9~84.3%. Therefore, these high-affinity VNAR binders showed promise as detectors and therapeutics of COVID-19.